On page 137 there's Alphabetical Index. If you update it, it goes away.
check page 137.odt (application/vnd.oasis.opendocument.text), 5.29 MB, created by r@fael.lv on 2016-11-17 19:27:58 UTC
(hide)
 
Creator: r@fael.lv
Created: 2016-11-17 19:27:58 UTC
Size: 5.29 MB

Attachment is not viewable in your browser because its MIME type (application/vnd.oasis.opendocument.text) is not one that your browser is able to display.

Download the attachment.

Actions: View
Attachments on bug 103059: 128091 | 128826